Variable pitch propeller



April 18, 1944. p LILLEY 2,346,979

' VARI ABLE PITCH PROPELLER v Filed Aug. 13. 1940 9 Sheets-Sheet 1 A INVENTOR- BY DAN/EL 6: Z/LLEY.

dfiarney April 18, 1944. D, L y 2,346,979

VARIABLE ncn PROPELLER Filed Aug. -13, 1940 9 Sheets-Sheet 2 /2/ F 6 INVENTOR.

' DAN/EL 6. 1/445) ATTORNEY. v

April 18, 1944.

D. G.'LI LLEY VARIABLE PITCH PROPELLER INVENTOR.

DAN/EL l/Lusy WMW ATTORNEY.

9 Sheets-Sheet s April 18, 1944, L Y 2,346,979

VARIABLE PITCH PROPELLER Filed Aug. 13, 1940 9 Sheets-Sheet 4 iNVENTOR BY DAN/5L6 Z/LLEY WW%F'6LW ATTORNEY.

April 18,1944. D. G. LILLEY 2,346,979.

I VARIABLE PITCH PROPELLER Filed Aug. 13, 1940 9 Sheets-Sheet 5 INVENTOR. DAM/2.4 4/445)? I AORNEY.

D. G. LlLLEY VARIABLE PITCH PROPELLER ATTORNEY.

Y E L H L G D VARIABLE PITCH PROPELLER Filed Aug. 15, 1940 9 Shgets-Sheet 7 v INVENTOR. BY DAN/EL 6 Luusy ATTORNEY.

April 1 D. G. LILLEY 2,346,979

VARIABLE PITCH PROFELLER Filed Aug. 15. 1940 9 Sheets-Sheet a INVENTOR. v

DANIEL 6. .L/LLEY W r W ATTORNEY.

April 18,1944. v 2,346,979

' VARIABLE PITCH PROPELLER Filed Aug. 13, 1940 9 Sheets-Sheet 9 A BC-DEF Hum 9a INVENTQR. DA /E1. 6. 'L/LLEY WWWM' ad-la mvey vention is to provide an automatic variable pitch so much lost motion.

' mechanisms, and especially so in the governor PatenteHApr.18, 1944 g 1 2,346,979

UNITED STATES PATENT OFFICE VARIABLE PITCH PROPIELLER Daniel G. Lilley, Denver, Colo; Application August 13, 1940, Serial No. 352,352

. 30 Claims. (Cl. 170-163) This invention relates toimprovementsin vari- 'peller to contact orbit the blade at the same able pitch propellers of the type employed in conrelative rate of speed as required in Case (A), nection with aeroplanes. the force ofthe wind driving the propeller wind- It is well understood that for the greatest eilimill fashion would produce as much power as was ciency of operation, means must be provided for 5 consumed by the engine in Case (A), but in this changing the pitch of the propellers so as to get case the thrust action upon the drive shaft would maximum traction while leaving the ground and be in the reverse direction. Here it will be noted maximum speed while inthe air. that the air will be moving relative to the blades, Various types of variable pitch propellers have which differs from Case (A) in which case the been invented and shown in various patents hereblades are moving relative to ti e air, however,

tofore granted. the relative rate of blade and'air hitting speed One of the most important objects of this inwould be the same in both cases.

propeller of the constant speed type which shall case (0) be provided with manually adjustable stops for Instead of the generator, suppose the engine limiting th pitch angle adjustment while t is again connected with the propeller drive shaft propelleris operating. 1 Th im t of such and driven at the same number of R. P. M. as variable stops can best be appreciated from the required in Case (A), that a head wind is devellollowing description and explanation oi the the- Oped of the same velocity as n Case (B) Here cry and operation which will now b set out for we would have two oppositely disposed thrust actms purpose' I ft 21 t allz th thrust t r sha eac neu r ing e ac ion orce INTRODUCTORY STATEMENT of the other, whereby the thrust action upon the No matter where wind is encountered, on the drive shaft would be reduced to'zero in either ground or in the air, 11' it blows head on, and sub- 25 direction. staiitiatlllygarallel to the axis about which apro- Case (D) De er it is windmill action and as far With all factors such as blade pitch, propeller propeller thrust efficiency is concerned, it is just R. P. M" etc the same as in c (A and ffiwhere such winds are of any appreciable should a tail wind be set up, then the thrust e tion. forces working at cross purposes on the same er 10cm, they produce a mu" m the operation and ciency of the propeller would be increased o v and above Case (A) in lineal rate of travel during, flight, commensurate with the speed and force of the wind coming into contact with the controlled type. A similar fault is brought about ling 11 r bythe action of tail winds. The following theory tractive effort sine of the wmr prope 6 control of automatic variable pitch propeller blades. explains the Team It will be pointed out that the propeller will be Case (A) turning in the same direction in all four of above In a re ll of an w n l h mentioned cases, and it will be noted that each mounte gl 0g; driv 5 1'5 :ggfigf, 3 2 3; case represents a different combination of relagiven den ity, a nthat is still relative to the 49 tive movement between air and propeller blades,

round. if To Her thrust acfl only two of which are adaptablefor producing s to a gflefiumber of gg g gz fffi thrust of standard value or above, where operaln the direction of its tractive effort, it will reis under given constant speed number of quire an engine of given power t ut fo mt t propeller R- P- M" as in Cases A and D.

ing the propeller at a given number of R Case (C) represents an extreme case oi'a cross Y relative to the air. and the movement of the between Propeller action as Case (A) and blades relative to the air will have to reach a cerwindmill action as in Case (B) Here on the tain rate of hitting speed or velocity relative to pmpeuer side the operation the wind is travel the air before the givennumber of poundsthru'st g,

ing away tromitheiback tractiveislde ne -blades st te they would eetle l U in ktillcain."frlt isaythereijore impo le, for tne-pacaeslwmit thenimitlr-anr creel-audience fiiis liittir'ig-iiorcetiss reduced to 9 fiQQigQfiH be I thi'usttitraveliiofiltlyetplfmfillfih gfifi iieia "83? at action will be produced,

CaseAB) miauon awm mumee tneeenziae unlae ienciiazim aria hnlw'oli i lo qiiiooiev erii io moi .ls lleqi'mq exit lo hesqa we?! eitini'rev s aexnoo two i eration 'i'sqbirg 2 with no tractive resistance for it to work against.

On the windmill side of the operation, since the engine will be rotating the propeller at the top number of R. P. M., the forward or tractive effort side of the blades will be turned out of the wind as fast as the latter could drive the propeller working against a generator as in Case (B), and would be unable to develop any thrust eiTort along the axis'of the drive shaft windmill fash- -ion. This is a case where two oppositely disposed thrust action forces are at work on the same shaft, fighting each other for control of the blades to see if the latter shall serve as a propeller or a windmill.

It is apparent from the above that when the cannot perform properly working under the influence of two variable factors.

The foregoing theory explains how a head wind will interfere to change the propeller thrust force from a stabilized force into a variable force, by causing a loss in the rate of hitting speed and movement of the blades relative to the air, in the speed of an engine is restricted so as not to exceed a given number of R. P. M. the propeller thrust efficiency will be of normal value only so long as the operation is entirely free from head winds, that the thrust efllciency of the propeller will be subnormal to the extent of the velocity of the wind to the rotational speed of the propeller.

While Case (A) specifies a fixed pitch propeller, a governor-controlled propeller would develop the same amount of thrust e'fl'ort at the same number of engine and propeller R. P. M., provided the governor is in proper adjustment. since in this case no wind or movement of air relative to the propeller is involved, the blades would automatically assume the same pitch as the fixed pitch propeller, assuming the latter has the correct pitch.

- In the operation of governor controlled propeller mechanisms, the value of ship drag, and the" value of propeller thrust constitute the two main forces entering into this type of propeller control.

In conjunction with these two forces the governor operates'to equalize the power output of the englne between ship-drag and propeller thrust. It

' propeller. The ship and propeller will be movin relative to the still air, and there will be no move ment of the air itself relative to the ship and propeller. In this case with the engine and propeller restrictedso as not to exceed a given speed (R. P. M.), the blades will have a comparatively constant 'rate of hitting speed relative to the air, and the air will have a comparatively constant tractive resistance value at a given altitude for the engine and propeller to work against.

This condition will give the propeller a stabilized thrust action to serve as a dependable base force, to and from which the speed responsive governor can operate to adjust the thrust. position of the blades to compensate for variations of the variable ship-drag force, caused by variations in air density. So long as the thrust force maintains a stabilized value with respect to the variable ship-drag force, the governor will perform its function perfectly and alter the blade pitch according to variations in ship-drag.

However, just the instant a head wind creeps into the operation the thrust force of the propeller will lose its stabilizing influence to the extent of the velocity of the wind to the rotational speed of the propeller. The thrust force then becomes a variable factor, and the governor will lose proper control over the blade P tch, it simply changes the angle at which the blades contact:

proportion of the velocity of the wind to the rotational speed of the propeller, under which condition the thrust force of the propeller is bound to drop, and where there is a drop in the propeller thrust value there will be a corresponding drop in ship-drag and loss in relative ship and air speed, which action will partially unload the, engine, allowing the latter to go into the top number of cruising R. M. P., at which R. P. M. the governor will operate toincrease the blade pitch out of proportion to air density. This action prevents such mechanisms from maintaining a blade pitch commensurate with air density and ship-drag.

If normal relative ship and air speed is to be maintained in a head wind, the ship-drag against the propeller must work will be the same as in still air-operation, and the same. value in propeller thrust efllciency will be required; therefore it is important that the same blade pitch be maintained as before the wind was encountered. together with a sufficient increase inthe number of engine and propeller R. P. M. to make up for the velocity of the wind, to restore the normal rate of blade hitting speed relative to the air. In

this way only can normal relative ship and air speed be maintained where the ship is held in' level or horizontal flight by a robot pilot.

To allow an increase in blade pitch under the above circumstances is to sacrifice propeller thrust efllciency in order to increase the effect of blade torque to hold down the number of engine R. P. M. To so increase the blade pitch merely or hit the air, it does not change the rate of blade hitting speed relative to the air to make up for the velocity of the wind which has robbed the propeller blades of their normal rate of hitting speed relative to the air. 1

Since the value in ship-drag and relative ship and air speed should be the same operating-in still air or ma head wind, it is apparent that any increase in blade pitch caused by a head wind is not in order, and is just as wrong as it would be to employ the same advanced blade pitch in still air operation in the first place.

The danger .of increasing the blade pitch due to head winds is not quite so dangerous flying at some high altitude, where the blades already have a normal pitch close to the maximum pitch allowed by the blade pitch limiting stops, but should this happen at a comparatively low altitude where the normal mean operating pitch is in some intermediate position considerable distance back of the maximum blade pitch limitingstops, there might be grave danger, should the loss in blade torque reaction due to an extremely hi h velocity wind cause the mechanism to move or Jump the blades too far beyond normal pitch position. They would be free to go all the way through to the maximum limitin stops provided the wind is of high enough velocity.

In the operation of governor-controlled propellers, it has been customary to caution, pilots not'to'exceed a given number of engine R. P. M.,

for the reason that such increase in engine speed (R. P. M.) will causethe governor to increase the blade pitch out of proportion to air density,

whereby the pilot would have to readiust the governor to suit each change in into the top number of cruising R. P. M. Whenever this happens, it sets up a fault, or leak for a still further loss in propeller thrust value by operating the governor to increasethe blade pitch, which is not in order, and if allowed to occur, will result in a blade thrust position out of proportion to air density and ship-drag.

Provided a pilot discovers head winds in time. they can be compensated for by increased tension of thegovernor control spring, together with a corresponding increase in engine R.'P. M. Such measures however are apt to be rather diillcult number of engine caught suddenl in the path of a high velocity tail wind, it will suiler a loss in air speed and ship to the suddenness and velocdrag corresponding ity of the wind.

The loss inship drag will have the effect of partially unloading the engine, allowing the latter to speedup enough to influence the governor to make a corresponding increase. in blade pitch.

Where a tail wind is allowed to arbitrarily increase the pitch commensurate with loss in ship-drag. the propeller is very apt to sufller a greater percentage of loss in propeller thrust action than the percentage of loss in ship-drag,

on multi-motored ships, especially under violent,

gusty, head wind conditions.

It can be seen from the foregoing, that the influence of variations in propeller torque reaction upon the engine serves as the initiating factor for altering the thrust position of the blades to conform with variations in ship-drag.

It can also be seen that it is safe to allow an increase in blade pitch out of proportion to air density and ship-drag only when there is an easing oil in ship-drag upon the engine and propeller, as for instance where the plane is nosed downward into a dive or glide, in which case the engine can still be operated at any desired constant number of R. P. M., and the propeller thrust action made to cooperate with the force of gravity acting upon the ship throughout a prolonged dive or glide merely by the provision of an adjustable maximum blade pitch limiting, means, and the movement of same well'toward full feathering pitch position so as not-to interfere with a, wide increase in blade pitch, whereby the governor will operate to alter the blade pitch commensurate with the number of engine R. P. M. and the velocity of the ship, and thereby prevent windmill action from driving the engine at an V excessive number Of R. P. M. a y

In such operation, while the influence of propeller thrust will become less and less as the blades are moved toward full feathering pitch position, whatever thrust s developed will be just that much in cooperation with gravity acting upon the ship, whereby phenominal speeds may be obtained in glides to objectives over comparatively long distances from high altitude positions. Continuo'us propeller thrust action during prolonged dives or glides would have a much better stabilizing influence upon a ship in the guidance of the latter than where windmill action is allowed to act as a brake against the descending force developed in the progress of the plane, to say nothing normal value.

whereby the propeller might not be left with enough thrust value to maintain flight under the reduced ship-drag caused by the tail wind.

Whereas, if the propeller blades were held'in a pitch positionsomewhere near normal, or commensurate with air density, the propeller would have its normal rate of thrust travel plus the velocity of the tail wind. This would insure that the'value of ship drag and control of the governor would remain under the powerful influence of propeller thrust action at all times.

Should the increase in blade pitch be so wide as to reach or pass a point where the, propeller could not produce enough thrust value with which to pick up the inertiaof the ship and regain air speed and ship-drag, the control of the governor would then pass from under the influence of propeller thrust action.

Control of the governor will remain under the influence of propeller thrust only so long as there is sufllcient thrust value to pick up the inertia and'air speed of the ship to restore the value of ship-drag, which factor operates to reload the engine and with the cooperation of blade torque reaction, slows down the R. P. M. of the engine to a point where the governor will operate the mechanism for reducing the blade pitch towards normal value, commensurate with air density, as fast as the drag of the ship is returned toward If a tail wind will unload the engine'by causing a loss inship-dragvalue, nothing but propeller thrust action will restore the value of ship-drag for reloading the engine where a ship i maintained in absolute horizontal flight, therefore the blade pitch must never be so far advanced that the propeller will lose its thrust influence over the value of ship-drag, and in turn control of the governor.

The instant propeller thrust value drops to a point -where it is unable to restore ship-drag value, at that instant thrust action surrenders pen in flying at some low altitude, the above men-' I tioned complication is ver apt to develop.

A pilot might not be aware of any danger until I the engine begins, to buckun'der the load due to the extreme advance blade pitch as the engine will be allowed to operate at top number of cruis-' ing R. P. M.,' up until just before the bucking action sets in. This buckin action will set in as soon as the ship loses a certain amount or air speed.

Since the propeller serves as the power transmission mechanism between the power plant and the plane, maximum overall efllciency 0f the 4 power plant and the plane cannot be developed until maximum propeller thrustefliciency is developed by means of a blade pitch commensurate with air densityand ship-drag, whereby a minimum number of engine and propeller R. P. M. is converted into a. maximum amount of relative ship and air speed.

. Therefore, maximum overall eillciency oi the plane and its power plant should not be considneously as the wind is encountered, is equally as important in tall as in head winds, the same adiustment normally being required in either case to limit the blade pitch to a safe position commensurate with air density.

It is therefore among the objects of this invention. to provide a safety blade pitch limitin or motor control means for governor controlled variable pitch propeller mechanisms, to render such mechanisms ineffective to increase the pitch of the blades beyond predetermined limits commensurate with air density irrespective of engine and propeller R. P. M., whereby the latter can be operated at normal cruisin R. P. M., under To provide a hydraulic system in which the control valve and all pipe lines entering into operation of the system arelocated close to the engine whereby the heat from the latter will prevent ireezing of any of 'the pipe linesfas might be the case where a plane is forced to land due to any cause in subzero weather; I I

To provide a motion transmission member operatedby the movement of the motor and mounted for operation in a path between the motor and the motor control means, means for creatin lost motion between the motion transmission member and the motor control means, and adjustable means for altering the extent of lost motion between the motion transmission member and the motor control means for adjusting the point at which the motion transmission member will operate the motor control means for controlling the operation oi! the motor when the propeller blades reach a predetermined pitch p0- sition;

normal flying conditions, or a higher R. P. M. to

compensate for head winds without increasing the pitch oi! the blades, and to enable the pilot at any time to increase the engine R. P. M. to

meet any emergency, accomplish any maneuver without fear of increasing the pitch of the blades out of proportion to the density. of the air in which the plane is operating.

In illustrating the invention, applicant i also disclosing improvements for the operation of hydraulic propellers of the types covered by Patents 1,894,047 and 1,894,048, both dated January 10,-

1933, in which relatively rotating connections are avoided in the oil pressure lines for operating the blade pitch changing mechanism by putting the pump on the drive shaft along with the hydraulic motor, and whereby, with the improvements enumerated herein, the propeller can be operated To provide manual means for selectively controlling the pitch of the blades from any desired minimum pitch position to full feathering pitch position, and to hold them in an selective pitch position in opposition to the action of the speed responsive means. in case the latter is employed. and to provide constant lubrication for the relatively rotating valve control parts;

To provide means for forcing the pitch of the blades to synchronize where two or more propellers are employed on ths same ship. This is important if absolute equal distribution of propeller thrust power is .to be brought to bear upon a ship;

To provide a control valve located between the pump and the motor, said valve having ports that serve alternately as intake and exhaust ports, and a separate. neutral exhaust port, allowing a liquid to flow unrestricted from the pump, back to the pump sump until such time as it is needed to drive the motor for affecting change in blade pitch, thereby abosrbing no appreciable amount of engine power, except as the motor for moving the blades is caused to operate;

'To provide a variable pitch propeller in which the motor means by which the blade pitch is adjusted is controlled to render the motor inopeither as a constant speed, as an automatic variable pitch, or in a selective pitch manner, independent oi', or in opposition to the action of a speed responsive means of blade pitch control.

Another object of the invention is to provide a hydraulic system comprising a pump for causing a continuous forced circulation or a liquid, with a blade pitch control valve located in the hydraulic circuit between the pump and motor, whereby the liquid from the pump can be diverted for operating the motor in either of two directions, or

- by-passed back to the pump sump without having to pass through the motor and in which system a spring pressed relief valve is avoided.

Other objects are to provide means for moving the motor control or blade pitch limiting means into an'extreme advanced position for the duration of- Prolonged power dives or glides, to enable the governor control mechanism to control the pitch of the blades during such manuever between. blade torque reaction and windmill action, whereby the pitch of the blades will be automatically adjusted commensurate and simultaneously with the increasing or decreasing velocity or the plane;

erative to further increase the pitch by three separate means, one of which is responsive to pitch, thereby absorving no appreciable amount speed and the third being manually controlled so that the pitch at whichthe other two become operative can be predetermined by the pilot.

vA further object of the invention is to provide an air density responsive device for altering the extent of lost motion between the motion transmission member and the motor control means commensurate with variations in air density.

A still further object is to provide for an increase in thenumber of engine R. P. M. as the only means by which head winds can be successfully met, enabling the pilot to watch his air speed indicator, and increase the engine R. P. M. enough above normal cruising R. P. M. to make up for the velocity of the wind or until the air speed indicator shows the plane has normal air DESCRIPTION.

'- in order to describe this invention and the means employed to obtain the objects and purposes above set out, reference will now be had to the accompanying drawings in which the invention has been illustrated in its preferred form,

' and in which:

section taken on line Figure is a transverse section taken on line 5-5, Figure 1;-

Figure 6 is a section taken on line 6-6 Figure Figure 7 is a section taken on line 1-1, Figure 1;

Figure 8 is a section taken on line 88, Figure Figure 9 is a section taken on lines 3:9, Figure 3, 6 and 7 Figure 10 is a fragmentary section similar to that shown in Figure 1 and shows a slightly modifled construction;

Figure 11 is a viewpartly in section and partly in elevation showing a mechanism provided with a series of levers positioned within easy reach of the pilot for controlling the pitch varying mechanismof the propeller;

Figure 12 is a section taken on line I2I2, Figure 11;

Figure 13 is a section taken on line I 3l3, Figure 11;

Figure 14 is a section taken on line |4l4,,, Figure 11; I

Figure 15 is a section taken on line l5-l5, Figure 11; v

Figure 16 is a section taken on line lB-iG, Figure 11;

Figure 17 is a section taken on line Ii-ll, Figure 11; e

Figure 18 is a section taken on line l3-I8, Figure 11; h

Figure 19 is a section taken on line l9-|9, Figure 11; T

Figure 20 is a diametrical section through an aneroid barometer of a large size whose function is to effect changes to compensate for air density;

Figure 211s a side elevation of a spring clip looking in the direction of arrows 2l-2 I, Figure 20;

Figure 22 is a, diagrammatic sectional view intended to illustrate the position of thesprings shown in Figure 20; I

Figure 23 is a view showing a bell crank lever mechanism whose function is to adjust the position of the barometer;

Figure 24 is a view partly in section and partly in elevation showing a diagrammatic representation of a modified form of construction;

Figure 25 is a fragmentary view showing a detail of the construction;

Figure 26 is a viewpaftly in section and partly in elevation, showing a still further modification Figure 27 is a section taken on line 21-47, Figure 26;

Figure 28' is a fragmentary detail similar to that shown in Figure 25;

Figure 29 is a detail view showing in elevation two interconnected parts of the mechanism;

Figure 30 is a side elevation showing one form of adjusting mechanism;

Figure 31 is a section taken on line 3l3|, Figure 30;

- designated by reference numeral 2|. Reference Figure 32 1s a fragmentary section taken on line 32-32, Figure 30;

Figure 33 is a modification of Fig. 26, showing a specifically different motion transmission mechanism;

Figure 34 is a fragmentary section showing another modification of Fig. 26, in which a manually controlled stop limits the increase in the pitch angle; and

'Figure 35 is a diagram employed in connection with the explanation of the operation.

In the drawings reference numeral 20 desig nates the propeller shaft which in a construction where the propeller is directly connected with the engine may also be the crank shaft of the engine,

but where the propeller is connected to the engine by means of gears for the purpose of obtaining a gear reduction shaft 20 is positioned parallel to the crank shaft and connected with the latter by means of suitable gears, one of which has been numeral 22 designates a. wall of the crank case of. the engine and reference numeral 23 designates the top wall of a gear case which is positioned to the front of the crank case. The upper wall is provided with an opening 24 that is closed by a cover 25 held in place by suitable bolts 26. The front wall of the gear case has been designated by reference numeral 27 and the bottom by ref-' erence numeral 28. Reference numeral 29 designate the propeller shaft bearing in the crank case wall and reference numeral 30 the bearing in the front wall of the gear case. The bearing 30 has been shown as an ordinary ball bearing? and this is held in place by means of plates 3| 3 and32 that are secured to the. wall 21 by means of bolts 33. The propeller shaft is hollow and reference numeral 34 designates the wall of the opening therein.

In the embodiment shown, thepropeller shaft is made in two parts, the front part having been designated by numeral 20a. The, part of the shaft designated by reference numeral 20 has an outwardly extending wall or flange 35 which terminates in a forwardly extending cylindrical flange 36 that is provided with threaded openings for the reception of cap screws 31. The rear end of the front part of the crank shaft is provided with an outwardly. extending wall 38 that terminates in 'a rearwardly extending cylindrical flange 39 which is provided about its rear edge with an outwardly extending flange 40 that is provided with openings for the reception of the cap screws 37. It will be observed that when the two parts 20 and 20a are assembled, they form a chamber between the two walls 35 and 38 and positioned within this chamber are various mechanisms which will be hereinafter described.

Referring now more particularly to Figure 6 it will be seen that the wall 38 is provided with three parallel passageways or openings extending from each side of a diameter. The central opening has been designated by reference numeral 4| and has beenshown by full lines in Figure 1. Positioned to the left of opening 4|, when viewed as in the upper half of Figure 6 is an opening 42 and a similar opening '43 is positioned to'the right of opening 4|. The position of openings 42 and 43 arereversed in the lower half of Figure 6. Openings-4i connect with longitudinall-yextending openings 41a in the shaft 20a. and openings 42 and 43 in a similar manner connect with openings 42a and 43a in the shaft.

Referring now more particularly to Figure 7,

it will be observed that wall 38 is provided on its rear side'with thickened parts 44 that form housings for gear pumps, the two gears of which have been designated by reference numerals 45 and 45. The discharge ports of these pumps have been designated by reference characters 4"), which are continuations of the openings 41, while the intake ports have been designated by reference numerals 41. The intake ports 41 are the terminals of the branches 48 of the opening 48 which in the actual embodiment is connected with the lubricating system of the engine in such a way that opening 49 always contains lubricating oil under considerable pressure. Secured to the thickened portions 44, by means of cap screws 50 are covers These covers are provided with openings 52 whose upper ends are in communication with the intake ports 41 and whose other ends-open into the chamber formed by the walls 35 and 33. Ball valves 53 serve a special function which will hereinafter be explained and normally prevent oil from flowing into intake ports 41 from the chamber between walls 35 and 38.

It is now apparent that if the gears 45 and 45 are rotated in the direction indicated by the arrows, oil will be transferred from the intake ports 41 to the outlet ports 4") and this will cause oil under pressure to fill the openings 4|a in that portion of the shaftdesignated by reference character 2 00.

The pumps are operated by the following mechanism. A sleeve 54 encircles part 20a of the propeller shaft and is held against rotation by splines 55, which interconnect it with the plate 31 in the manner shown in Figure 2. This interconnection holds the sleeve from rotation but permits the propeller shaft to turn therein. The

rear end of the, sleeve is provided with an outwardly extending flange 55 whose periphery is provided with gear teeth that mesh with corresponding teeth in gears 51. Gears 51 are nonrotatably connected with short shafts 58 whose other ends are connected with the gears 45 of the gear pumps. If we now assume that the parts rotate in the direction of the arrow in Figure 3, gears 51 will rotate about the axes of shafts 58 in counterclockwise direction as indicated by the arrows and this will cause the gears 45 to rotate in clockwise direction when viewed as in Figure I. It will therefore be apparent that whenever the shaft 20a is rotating, the two gear pumps will function'to transfer oil from the intake ports 41 to the outlet ports 41b and means must therefore be provided to bypass this oil or in other ways to prevent the formation of excessive pressures during operation. It will be seen from Figure 1 that openings 59 are provided in the wall of shaft 20a which extend from the openings M to the interior of the shaft and these openings serve as by-passes in a mannerwhich will presently appear.

Positioned in the shaft is a tubular valve. that has been designated by reference numeral 60. The outside diameter of this valve is such that it fits the inside of the crank shaft with a'slidi118 fit and the outer surface thereof has been provided vwith depressions or annular grooves.

threaded for the reception of a nut 16.

flange 69.

inner ends of plates 80 so that oil cannot flow to the motor in either direction, but when the valve member is in this position, groove 64 registers with the bypass opening 59 to permit the oil to flow into groove 64 and thence into the chamber between walls 33 and 35 and thence out through a plurality of openings 38a in wall 38, thus lubricating the various relatively rotating parts and is then returned to' the engine pump sump through opening 38b. The grooves SI and 63 are in communication at all times with grooves Bio and 53a and serve as exhaust ports in a manner which will appear as the description proceeds.

Referring now to Figures 1 and 8 it will be.

seen that a circular member 61 is positioned in the chamber between walls 35 and 33 and has an outwardly extending flange 68 that projects into the space between flanges 36 and 40 so as to be held in position by the bolts 31. Member 51 has an annular .rearwardly extending flange 59 to which a cover plate 10 is secured by means of screws or bolts 1|.

Referring now to Figure 8, it will be observed that the flange 69 is of different thicknesses along different points and forms an oblong chamber whose inner wall has been designated by reference numeral 12. The thickest portions of flange 69 are positioned at points 13 that are diametrically opposite each other.. A shaft 14 projects through openings in members 61 and 10 as shown in Figure l and a stufling box'15 is provided where this shaft goes through the opening in part 61.

A motor rotor 11 is positioned in the chamber formed by the parts 61 and 10 and the inner surface of This rotor is nonrotatably secured to the shaft 14 by means of splines 18.

' It will be seen from Figure 8 that the rotor 11 is provided with four radial slots 19 within which are slidably mounted plates. Helical compression springs 81 ar and the bottoms of slots 19. These springs serve to urge the blades against the inner surface 12 of flange 69 in a manner quite common in connection with rotary motors. It will be observed that four ports enter the pump,

two of which have been designated by reference numerals 42 and two by reference numerals 43.

If liquid under pressure is introduced through the ports 42, the pressure of this liquid acting against the plates 80 will produce a clockwise rotation of the rotor 11, but if the liquid is introduced through the ports 43, the rotor will rotate in the opposite direction. When one setof ports serveas intake ports, the other set will serve as outlet ports from the motor.

When the valve is Figures 1 and 9, the entrances into openings 43a and 420. are closed by the walls or ribs 56 and 55, respectively, and therefore oil can neither enter nor leave the motor. If valve 60 is now moved towards the right, the wall will pass to the right of the entrance into opening 42a and rib 65 will move towards the right of the entrance 43a. thereby connecting ports 42 of the pump with the exhaust groove BI- and connecting the inlet port 43 with the pressure groove .62 and at the same time closing the openings 59 by the rib 82. Oil will now flow through opening 431: and enter the pump through the ports 43, thereby producing counterclockwise rotation and at the same time any oil between the rotor and the. flange 39 will be exhausted through ports 42 and pass into the exhaust groove BI and from thence to The rear end of shaft 14 is positioned between the in the position shown in the interior of valve into the groove Bio from whence it will pass into the chamber between walls 20 and 38. If valve 80 is now moved towards the left to the position shown in Figures 1 and 9, the oil will be trapped so as to positively hold the rotor ll against movement in either direction. If the rotor is to be rotatedin the opposite direction, valve 60 is moved towards the left until rib 65 uncovers the opening into 42a, thereby connecting the same with the pressure groove 62 and at the same time rib 60 l uncover the opening into 43a, thereby conn ting the same be further explained as this description proceeds.

Valve 60 is provided at its inner end with radially extending arms I04, which are shown quite clearly in Figure '7 and secured to the ends of these arms are rods I05 that extend through the wall 38 and have their forward ends connected with ring 91 at diametrically opposed points as shown in Figure 5. 5

From the above it will be apparent that whenever ring ii is moved longitudinally, it will im-- part a corresponding movement to the helical bars 00 and they in turn will rotate the billions I00, whereupon the tubular stop I02 will rotate relative to the valve. 60 and whenever ring 91 moves longitudinally, it will transmit this motion by means of rods I05 to the arms I04 of the The position of the valve is controlled by means which will now be described. Attention has already been called to sleeve 54 which is held against tubular valve 00 and shift the latter for the purpose of controlling the flow-of oil to the motorv .and todetermine the direction ofrotation of the latter as well as to hold it in any desired position.

, Referring now to Figure 7, it will be observed that the tubular stop I02 is provided in addition rotation and which is provided on itsouter surv face with splines 55. Slidably mounted on sleeve 54 is a sleeve 84 whose outer surface is provided with splines 85. A sleeve 86 is mounted on sleeve 04 and its outer surface is provided with splines 01. It will be observed that the inner end of sleeve 04 has an outwardly extending flange 08. Sleeve 84 has a shoulder 00 against which the sleeve 00 abuts and the latter is provided with a flange 90 which cooperates with flange 80 to form a groove for the reception of ring 9i, which is rotatably mounted in the groove. A ring 92 is threadedly connected with the front end of sleeve 04 and serves to hold the sleeve 86 against the shoulder 89. A sleeve 98 is slidably mounted on sleeve 86 and splined thereto so that it may move longitudinally but not rotatably thereon. Sleeve 93 has a flange 96 and has its outer surface threaded as indicated by reference numeral 95. A circular ring 96 is threadedly connected with the sleeve 93 and adjusted in spaced relation with the flange 94 so as to provide a groove for the reception of ring 91 which can rotate freely in the groov thus provided.

Referring now to Figure 4, it will be observed that ring 9| is provided at diametrically opposite points with openings for the reception of helical rods 98 which are held against rotation with respect to the ring and whose, inner ends engage in helical grooves in the hubs 99 of pinions I00. Whenever sleeve 84 moves longitudinally on sleeve54; it. moves ring 0| in a corresponding manner and this motion moves the helical rods 00 with respect to the pinions I00 and thereby cause the latter to rotate about their axes. The pinions I00 are in operative engagement with toothed segments IOI, and therefore whenever these pinions rotate, they will produce a corresponding rotation of segments NH. The toothed segments IOI extend from a tubular member I02 which will be referred to as a stop and which extends into the valve 00 in the manner shown in'Figure 1 and therefore whenever the pinions turn about their axes, the stop I02 will rotate in a corresponding manner within the valve. A referenc to Figure 1 will show that the tubular stop I02 is provided on opposite sldeswith openings having helical walls I03 on one side. The

purpose and operation of the tubular stop will is to the radial segments IOI with, two radial extensions I0 that are provided with radial slots I01. Bolts or pins I08 are connected at their inner ends to the radial arms I04 and project through the slots I01 and since these pins. have enlarged heads, they hold the tubular valve 00 and the tubular stop I02 from moving relative to each other in a longitudinal direction, but permit them to have relative rotary movement. When the tubular valve is moved longitudinally in response to movement of ring'fll which carries with it the tubular stop and consequently the arcuate segments IOI move in corresponding manner along the pinions I00, which are made of considerable length so as to permit this ad- Justment while maintaining the pinions and segments in operative engagement.

'The rotation of shaft 114 varies the pitch angle of the propeller blades, one of which has been shown in Figure 1 and indicated by reference The propeller blade and pitch character B. adiusting mechanism has been shown diagrammatically as an extension of the main portion of Figure 1 and from this diagram it will be observed that shaft 14 is provided at its front end with a spur gear I09 which meshes with another similar gear H0 that is connected to one end of shaft III. This shafthas two worms H2 and I I3. The root portion of blade "3 is nonrotatably connected with a gear ,II4 and motion is transmitted to this gear from the worms H2 and M3 by means of worm gears H6, shafts H5 and pinions I I1. It will now be apparent that whenever shaft [4 rotates, it will produce a corresponding change in the pitch angleof the propeller blade and the direction of this change will depend on the direction of rotation of the shaft 14, which in turn is controlled by the direction in which the rotor 11 turns and this is controlled by the position of the tubular valvein a manner which has heretofore been described.

It will be seen from Figure 1 that shaft 14 has a threaded portion II8.on which is mounted a nut IIS. This nut is provided with fiiametrically extending projection I20 that projects through the openings in the tubular stop I02 and have their ends positioned in longitudinally extending grooves in the inner surface of tubular valve 60. It willnow be seen that since valve 60 cannot rotate, the nut, which is nonrotatably connected therewith, is also held from rotation, but is free blade. g

of stop I02 will be transmitted to the tubular valve and when the valve reaches the neutral position shown in Figure l, the operation of the motor will cease and this will determine theextent of the increase of the pitch angle of the It might be explained here that the parts are so adjusted that when the rotor" rotatesin a clockwise direction when viewed as in.Figure 8, it rotates shaft 14 in a direction-t0 increase the pitch angle and when it rotates in a counterclockwise direction, it serves to decrease the pitch angle. When the motor operates to increase the pitch angle, the nut IIO moves towards the right and when the motor operates to decrease the pitch angle, this nut moves towards the left. The direction of rotation of the motor is controlled by means which will be hereinafter described, and which comprises a lever that is pivoted at I22 and has arms I23 that are connected to pins I24 on the threaded ring 00.

Since the pitch anglesmust vary in accordance with the speed of rotation and since the latter is controlled ,to a great extent by the torque resistance offered by the propeller, it is desirable to control the pitch angle by speed re sponsive means and in the present embodiment centrifugal governors have been provided for this purpose. 1

In the drawings reference numeral I rep resents a weight at the end of arm I20 that forms part of a bell crank whose other arm has been designated by I21. The bell crank is pivoted at I20. The arms I2'I are forked so as to embrace the rods I00 and the latter are provided with pins I20 that engage the front sides of the crank .arms' 121. When the assembly is rotating the centrifugal force tends to rotate the weight I20. in a counterclockwise direction, about pivot I20 and this in turn produces a forcethat' tends to move the rods *I00,"together with the tubular stop and tubular valve, towards the left. When the valve is moved a sufficient distance towards the left to uncover the opening 420 in Figure 9, the motor will start operating to increase the pitch and this will continue until the increased resistlongitudinally a mechanism has been provided which comprises the lever I3I that is pivoted at I32. 1 Arms I33 connect the lever I3I with pins I34,

It is therefore is transmitted to the gear segment IOI, whereby the tubular stop member I02 is rotated about its axis. If we examine Figure 1, we will find that if the tubular stop I02 is rotated so as to brin the edge I03 downwardly, the projection I20 will be free to move farther towards the right. before they engage the stop and therefore the pitch of the blades will be adjusted to a greater ance slows the rotation sufllciently to permit the valve to be moved to neutral position by the action of spring I30 whose relationship to this part of the mechanism will presently be described. Unless the valve is returned manually to neutral osition, the motor will continue to operate until 7 that pinions I00 are rotated by means of hell cally splined rods 00 that are nonrotatably connected with ring 3| as shown in Figure 4 andfor the purpose of shifting the position of these rods 30 anglebefore the motor is cut off. Lever I3I can be manually or automatically controlled by means which will presently be described and in this way it is possible to effect adjustments while the propeller is operating which adjustments will determine the maximum pitch angle.

In Figure 1 reference numeral I30 represents a rod that is connected to the movable end of lever I2I and reference numeral I30 designates a similar rod connected to the free end of lever I3I.

- Referringnow to the right half of Figure 11,, it

rods I30 are pivotally connected to the ends of crank arms I30a. It will be observed that four sets of rods and crank arms are shown in Figure 11 which correspond to a four-engine aero-i I plane, there being one rod I30 and one rod I 30 connected with each propeller mechanism. The right half of Figure 11 controls one pair of engines. and propellers and the left half another pair, the two halves are of identical construction and the same reference numerals have therefore been used to designate the parts of identical construction and function. "Means is provided whereby the pilot may manually control the direction of rotation of the motor which changes theblade pitch and also the position of the tubular stop I02 and the mechanism by means of which this is effected has been shown inFigure 11 shows two sets of control members and the set located to the right of the figure has been shown partly in longitudinal section. In this figure each set is provided with four bearings which have been designated by reference numerals I31,

I30, I30 and I40. These bearings are secured,

to some stationary part of the ship which has not been shown in the drawings. Numeral I4I represents a tubular shaft that is rotatably mounted on a tubular shaft designated by reference numeral I42 and this in turn is rotatably mounted on a tubular shaft I43 while the latter is rotatably mounted on the tubular shaft I44. It will thus be seen that the four tubular shafts are concentric and are joumaled one on the other. Attached to the inner end of shaft I is a lever I40 that terminates in a hand grip portion I40. Whenever lever I45 is rocked this retates shaft I and imparts a corresponding rotation to the crank arm I300 which in turn transmits this motion to the connecting rod I30 and whenever this rod moves it rocks lever I2 I, thereby moving the ring 01 longitudinally and efl'ecing a longitudinal movement of rods I00 which in turn transmit this motion to the tubular valve 00 it is now evident that by means of the lever- I40, the pilot may move the tubular valve 0010agitudlnally so as to control the direction of motion of the motor that changes the pitch of the blades. Lever "So is connected with the tubuwhich is connected by means of a bolt or rivet I48 with a corresponding flange I49 of shaft I50. Another crank arm I35a is connected to the outer end of shaft I50 and therefore whenever lever I45a is rocked it will impart a corresponding movement-to the crank arm IlSa, whereby the valve 50 associated with the other propeller will be controlled in the same manner as already described in connection with crank arm I45. The arrangements of shafts, crank arms and levers shown to the right in Figure 11 is duplicated on the left of this figure and will therefore not be further described.

The position of the tubular stop I02 can be controlled by the pilot by means of the following mechanism. A lever I5 I is connected at'its under end with tubular shaft I43 and the latter can therefore be rotated by means of this lever. A crank arm I35a is nonrotatably secured to the outer end of shaft I43 and connecting rod I36 is pivotally connected with the outer end of this crank arm. The motion of connecting rod I36 is transmitted to lever I3I which in turn transmits the same to ring 9|, whereby the helical rods 08 are reciprocated'and pinions I are thereby caused to turn about their axes and to impart a corresponding movement to the tubular stop I02. A lever IIa is connected with the end of tubular shaft I44 to-the outer end of which a crank arm I36a is connected. By rocking lever I 5Ia the stop associated with the other propeller adjusting mechanism is controlled. For the purpose of controlling the stops associated with the other two propeller adjusting mechanisms, two other levers corresponding to levers I5I and I5Ia are provided.

In the foregoing portions of the specification, reference was made to a spring I 30 which was shown associated with the lever I2I,,the function of this spring being to produce a force that urges the rod- I05 towards the right when viewed as in Figure 1, thereby maintaining the pin I29 in contact with arm I21 of the centrifugal governor. Spring I30 was shown in Figure 1 mainly for convenience of description and springs performing the same function have been shown in Figure 11 and have been-designated by reference numerals I30a. The springs shown in Figure 11 are under compression and acton the crank arms I52 and I53 that are connected respectively with tubular shafts HI and I42. Referring now to Figure 12, it'will be seen that crank arm I52 encircles shaft HI and is held against rotation by means of splines I54.

Pivotally attached to the free end of crank arm I52 is a rod I55 that extends through the spring I30a and through an opening in a plate I50. Mounted in suitable bearings on plate I56 are two cams I51 and I58. The bearings have been designated by reference numerals I 59.. The two cams are interconnected by.means of sprocket gears I60 that constrain them to rotate in opposite directions. nected with one of the cams and is held in place by means of a nut I 62.. LeverIBI i positioned between guides I63. It will be seen from Figure 12 that whenever the lever IBI is turned in a clockwise direction, it compresses springs [30a and this in turn increases the resistance to move A lever I81 is ncnrotatably concentrifugal governors and by this adjustment the speed at which the valve 50 responds to a certain force exerted by the governor can he 5 varied.

Referring now. to Figure 12, it will be observed that the rod I55 is provided with nuts I54 against which the upper ends of springs I30a abut and these nutsserve as means for adjusting the tension of the springs to obtain equal tension against thecrank arms I52 and I53.

Reference numeral I65 indicates an antlfriction bearing. Numeral I50 designates abrak shoe formed on the free end of a resilient bar I51 that IS permanently attached to plat I58 by means of bolts I68. The tension of the bar I01 is such that the-brake shoe will normally engage the circular portion of crank arm I52. The pressure of this brake-shoe can be removed'by means of a cam I69 that can be controlled by means of a lever I10. When the cam is brought intodead center position, it will release the brake but when it,i moved away from this position, it will permit the brake to function. The function performed by these brakes is to produce a resistance of such magnitude. that the valve 60 will not respond to the action of the centrifugal governors and its position can therefor be adjusted by means of levers I45 and l45a and will re- 1 and it will also yield to the force exerted by the nut I I9 engaging the stop I02.

It is well understood that the density of the air diminishes with the altitude and that the lighter'or more rarefied air at higher altitudes does not offer the same, resistance to the propeller blades as the moredense air near the earth's surfac and for the best operation it is therefore desirable to increase the pitch of the propeller 4 blades in accordance with the altitude.

For the purpose of effecting an automatic pitch adjustment as the altitude increases, a mechanism responsive to air density has been provided and one embodiment thereof illustrated.

Referring now more particularly to 20,

a circular cup-like member whose cylindrical ides have been indicated by I13 and whose bottom has been indicated'by reference numeralflfl. A tubular guide member extends upwardlyfr'omlthe inner surface of the bottom and slidably mounted on this is a piston-like member I16 that has an upwardly extending tubular portion I11 that is provided on its inner surface with splines I10 which engage grooves in the guide member I15.

' The piston is somewhat smaller in diameter than the inside of the cylindrical body and is hermetically sealed to the latter by a flexible diaphragm I19 which is secured. along its lower edge to the piston and along its upper edge to the sides I13. A plurality of helical springs I80 are-arranged around the tubular guide I15 in the manner shown in Figure 22 and these springs tend to move the piston upwardly. The under surface of the bottom is provided with-two spacedlugs I8I between which is pivotally connected a link I82 whose lower end is pivoted to the free end.

of lever I83. If we now refer to Figure 23, it

ment which resistance opposes the action of the crank lever whose other arm has been designated by reference numeral I94. This bell crank lever is pivoted at I89 the pivot being carried by a bracket I89 that is secured to a portion of the airship fuselage I91. The upper end of lever I94 is provided with a ratchet mechanism comprising a pawl I91 that engages in ratchet teeth on the convex edge of a quadrant 39. It will be apparent that by moving lever I84, the barometer or air. density responsive device can be moved relative to the stationary guides I1I. The outer end of the tubular portion I11 is provided with a flange I89 to which is secured a metal body I99 that carries a plurality of pairs of spring fingers I9I. These fingers are provided on their adjacent surfaces with depressions I92 whose walls are bevelled.

Referring now to Figure 11, the fingers I9! are shown as embracing the levers II and I5Ia. From Figures 14 and 15 it will be seen that levers HI and IEIa are provided with pins I93 that will enter the depressions I92 when the levers are inserted between the spring fingers. If we now assume that the spring fingers are connected with the levers which control the tubular stop I92 in the manner shown in Figure 11, then all of these stops will be automatically adjusted in accordance with air density. The connection between levers ISI, I5Ia and the resilient fingers is not a positive connection due to the inclined sides of the recesses I92, but the pilot can by exercising sufiicient force detach any one of the levers from the finger clips and thereby control the stop of any propeller mechanism manually as distinguished from the automatic control that takes place when-the levers-are connected with the air density responsive device.

' relative rotation by means of splines.

In Figure 10, a slightly modified construction has been shown for the purpose of providing a mechanism in which machine gun bullets can be fired through the shaft 14. In order to provide this shaft with'an opening I94 of sufilcient size to serve as a gun barrel, the diameter of theshaft should be increased and in Figure 10 shaft 14a has been shown as substituted for the shaft 14. Since this shaft is somewhat larger in diameter the cooperating parts have been correspondingly increased in size and have been designated by similar reference characters.

Referring now more particularly to Figure 24 which shows a modified form of the invention, reference numeral I95 shows a portion of the crank case wall from which a wall I99 extends forardly and terminates in an end wall I91. Reference numeral I98 represents one part of the propeller drive shaft and this has a circular flange I99 that is connected along its peripherial edge to the flange 299 of housing portion of'the drive shaft. The part designated by reference numeral 11 is the rotor of the pitch adjusting motor that is shown in Figure 8. A tubular shaft 29I extends through an axial opening in the drive shaft and. terminates in a threaded end portion 292 to which a nut 293 is connected. A spur ear 294 is nonrotatably connected with the tubular shaft 29I so as to be rotated therewith and this gear corresponds to the spur gear I99 shown in Figure 1. .I

In the embodiment illustrated in. Figure 1 the control valve and the pump for maintaining the oil under pressure is carried by the rotating shaft,

whereas in the embodiment illustrated in Figure 24, the pump is carried by the crank case and a portion of Figure 24 is broken away to show a gear 295 that forms part of a gear pump which serves to maintain a constant flow of oil for use in operating the motor that changes the pitch of the propeller blades, A- gear 299 carried by the drive shaft'serves to operate the gear pump whenever the engine is running. The oil for use inoperating the parts is contained in a sump 291 from which a pipe 298 extends to the intake port of the pump and a pipe 299 extends from the delivery port of the pump to a pressure chamber 2I9 in the body 2 of a slide valve which will be hereinafter more fully described. When the rotor 11 is turning it carries with it the tubular shaft 29I because the two are held against A ring gear 2I2 is ,splined to the tubular shaft and this cooperates with a spur gear 2I9 that is carried by the shaft and which is nonrotatably mounted on a shaft 2 whose front end is threaded and engages in a threaded opening in the inner ball race 2I5 of a ball bearing whose oute ball race has'been designated by reference numeral 2I6. There are two gears 2I9 and two threaded shafts 2, which are operated in unison and therefore.

when shaft 2 turns in one direction, it moves the ball bearing towards the left and when it turns in the opposite direction it moves it towards the right. Two arms 2" are nonrotatably connected to a {bait 2I8 and extend downwardly on opposite sides of the ball race 2| 9 andhave their lower ends attached to the pivots 2I9 and therefore whenever the ball race moves longitudinally, it will rock shaft 2I9 about its axis. A lever 229 has one end nonrotatably secured to the shaft 2I8 and has a connecting rod 22I pivotally connected with its free end. The other end of this connecting rod is connected by means of a pivot 222 with the free end of a lever 223 that is pivoted at 224. It is now evident that .whenever the ball race 2I9 moves toward the right or towards the left, the lever 223, togetherwith the arm 229 which is integral therewith will rock about pivot 224. The purpose of this movement will appear as the description proceeds.

. Referring now to shaft 2I9, it will be seen that this is journaled in hearings in links 226 that are pivoted at 221. This link permits the shaft to move so as to prevent any binding action due to the change of angle when the ball race 2I6 moves.

Since the ball race 2I9 is operated directly from the tubular shaft 29I and since the latter by its rotation controls the pitch of the blade,

- it is evident that the movement of lever 229 corresponds to the pitch adjustment of the propeller blade and arm 225 serves as a pitch indicator for a purpose that will hereinafter appear. The valve body 2 has a chamber 2I9 and has a central cylindrical opening 229 in which is positioned a slide valve 229. Chamber 2I9 is connected with the opening 228 by means of ports 239 and 23L On the other side of the valve body. it is provided with a longitudinally extending opening 232 that is in communication with the cylindrical opening 229 through four ports which have been designated as a, b, c and d. A movable part of the slide valve which has been designated by reference numeral 229 is provided with annular recesses that have been designated by reference numerals e; f, g, h and i. The wall of the valve body has two openings which have been designated by 42:: and 431:. These openings or ports are in communication with conduits 4211 and 431 respectively. When the engine is operating with the parts in the position shown in Fi ure 24, the pump will draw oil from the sump v 201 and discharge it through pipe 209 into compartment 2l0 from which it flows through the annular recess h and passes through the port that the upper end of the slide valve 229 is provided with a chamber 233 in which is rotatably positioned a head 234 that is integral with the lower end of a rod 235. This rod extends upwardly through a hollow shaft 235 and terminates in a cross piece 231 which extends through slots 235 in the wall of the tubular shaft. Shaft 235 is rotatably mounted in a bearing 239 formed in a member stationary with respect to the fuselage and is held against downward movement by a collar 240. Secured to the upper end of shaft 235 is a plug or cap 241 which is provided with diametrically positioned ends or lugs 242 to which the upper ends of the governor arm 243 are pivoted. These arms carry balls 244 and have pivotally attached to them at points 245 links 245 whose lower ends are pivoted to the cross bar 231. The tubular shaft is provided with a bevel gear 241 that is driven by a similar gear 24! carried on shaft 249 to the other end of which a spur gear 250 isattached. This spurgear is in mesh with gear 205 on the drive shaft and therefore the governor will rotate at a speed corresponding to the speed of the drive shaft. It will now be apparent that when the speed increases the governor balls 244 will move upwardly and carry with them the rod 235 which in turn moves the slide valve 229 upwardly. When this valve is moved suiliciently to uncover port 421: oil under pressure will flow from the chamber 2|. through port 420:, thence 'through conduit the port 43:: in communication with the pressure chamber 2 l0 and port 421: in communication with theannular recess g which is in communication with the vertical passage 232 through opening b.

when the parts are in this position, the motor shown in Figure 8 will rotate in a direction to decrease the pitch. The parts are so adjusted that when the speed has a predetermined value, the slide valve is positioned as in Figure 24, which permits the oil from the pump to circulate freely from the sump through pipe 208, through the pump, thence through pipe 209 into the downward passage 232 and into the slgnp 201. Whenever the rotor turns it'also turns the shaft 2M and this in turn rotates the threaded shaft 2 l4 in a direction to move the ball race 2I5 towards the left when viewed asin Figure 24. This movement is transmitted to lever 220 which moves in to conform to varying conditions and for this purpose manually operable means have been provided for effecting a selective adjustment. It

will be observed from Figure 24 that the arm 25! is pivoted at 253 and is provided with a gear segment 254. A pinion 255 is secured to a shaft 255 and held in operative engagement with the gear segment 254. A lever 251 is nonrotatably connected with the shaft 255 and therefore by rocking this lever about the pivot 255 arm 25l will be rocked about pivot 253. A detent comprising a springpressed pawl 255 holds lever 251 in adjusted position. It is evident that if lever 251 is moved; so as to impart a clockwise rotation to arm 25l, the latter will engage the top of member 252 at a smaller angle than if it were in its present position and this adjustment makes it possible for the pilot to control pitch angle during flight.

In cases of emergency it may be necessary for the pilot to render the automatic pitch adjusting mechanism inoperative and to set the propellers at what he believes to be the most desirable pitch under the circumstances and for this purpose the mechanism has been provided which will now be described.

The slide valve shown in Figure 24 and the I parts secured to the upper end thereof are shown 421 and into the motor entering the latter as taken on line 24-24, Figure 25, and the latter is a view looking downwardly along plane 25-25, Figure 24. It will be observed that the top cover of the slide valve cylinder, which cover has been designated by reference numeral 259, extends to one side of the cylinder and is provided with an upward projection 250 that forks and terminates in two upwardly extending arms 25l that are provided with bearings 252 in which the pivots 263 are journaled. Mounted on the pivot 253 is a body having its lower surface 254 cylin-,

gaging the cylindrical surface 254 and holding the body against movement about pivots 253. Lever 210 is mounted on the plug 255 and has a cylindrical portion 2" that has opening for the reception of plug 255.

, in place by means of a nut 212. Lever 210 can a clockwise direction and transmits a corresponding movement to lever 223. When the maximum pitch desired has been reached, the arm 25l will engage the upper end of the hour glass shaped,

member 252 and any other increase in the blade angle will force the slide valve downwardly into neutral position whereupon all further movement will stop. It is often desirable for'the. pilot to adjust the maximum pitch of the propeller blades be rotated about the center of plug 255 from the full line to the dotted line positions shown in Figure 25 ,When this lever is in full line position, it engages in the. depression between the ends of member 252. and can therefore control the movement of the slide valve when force is applied to this lever. The friction between the surface 254 and the brake shoe"is sufficient to resist the action of the governor and it is therefore possible for the pilot-to take control from the governor and to hold the slide valve in neutral position or to increase or decrease thepitch of the propeller blades to any extent he may desire within the limits of the mechanism.

In United States Patent No. 2,032,255, granted February 25, 1936, a propeller mechanism has been shown in which the blades have attached two inertia members that function to increase the pitch of the blades in accordance with the speed of the propeller. This patent is also provided with a flow of oil from a power operated pump located in the maximum This lever is held 

